Here are all the lyrics from the songs:
http://themusicallyrics.com/p/426-the-prom-the-musical-lyrics.html
here is a plot synopsis:
http://themusicallyrics.com/p/426-the-prom-the-musical-lyrics/6639-the-prom-musical-plot-synopsis.html
Took me about 2 seconds to Google. Just read and opt out if you don't want your child to go.
As to Bible stuff in high school: Just go to a chorus concert or hang around during any "Winter" concert. In addition, there are numerous clubs and in some schools Bible study before and after school.
As to the swear words, the use of masturbation, and lose virginity - again, this may not be in your comfort zone. My 13 year-old 8th graders had heard a lot more than that in school from other kids and it did not turn them bad or evil or promiscuous. Same with some of the novels they have read in and out of school, and the movies they have seen in and out of school. My kids are strong enough in what they believe and who they are that the musical will not change that. Others may not be - so that is why parents can opt out.
Finally, instead of posting here, why not go and ask Josh Bickford if he has an agenda? Ask him and see what he believes.